This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application A METHOD OF CONTROLLING A GAIN OF A VIDEO SIGNAL IN A VIDEO DISPLAY SYSTEM filed with the Korean Industrial Property Office on Dec. 24, 1999 and there duly assigned Serial No. 62057/1999.
1. Technical Field
The present invention relates to a device and a method for controlling a red, green and blue(RGB) video signal gain and, more particularly, to a device and a method for controlling a video signal gain, enabling R, G and B gain values to be controlled with difference values calculated through a comparison of count values of colors controlled by a user with count values of the other colors not controlled by the user.
2. Related Art
In general, the cathode ray tube (CRT) is widely used as a video display device due to a low price and an excellent display performance. Different amounts of electron beams, according to the intensity of a video signal, strike R, G, and B fluorescent materials coated on the surface of the CRT so that different colors with different brightnesses are displayed.
In general, various methods for controlling the gain of a video signal have been provided. However, such methods have been burdened by problems or disadvantages. For example, some methods are such that, in the case of a display having high brightness, that brightness exerts an adverse influence on focus of the display. Moreover, the brightness and color coordinates can become distorted. Other methods resolve some of the aforementioned problems, but cause other problems. For example, in such methods, the brightness becomes too low if all colors of the display have maximum values. Moreover, the brightness and color coordinates are still distorted as mentioned above relative to the first group of methods.
A method for varying some color gains based on difference values before and after varying the other color gains is disclosed in Japanese application No. 7-274014(laid-open date falls on Oct. 30, 1995) entitled xe2x80x9cMethod for Varying Display Colorsxe2x80x9d. The latter discloses a computer system having a device for outputting a screen constituted with plural items capable of displaying colors, which includes: an input control part for setting color information in a memory after varying corresponding items based on a color variation instruction with respect to one arbitrary item provided by an input device; a variation control part for obtaining a variation value of color information after varying the corresponding item set in the memory by the input control part and reflecting the variation value to a color variation of other items; and an output control part for setting, in the memory, color information after varying a prior item based on control of a color variation based on the variation control part, and controlling a color variation output of the screen outputted based on the corresponding color information in the memory. However, the above invention(Japanese application No. 7-274014) has a problem, as in the second method described above, in that brightness and color coordinates are distorted, even though RGB gain values are actually varied at the same level.
In order to solve the above problems, it is an object of the present invention to provide a device and a method for controlling a video signal gain, enabling R, G, and B gain values to be controlled with difference values calculated through a comparison of count values of colors controlled by a user with count values of the other colors not controlled by the user.
In order to achieve the above object, the device according to the present invention comprises: a key input part having a color selection key and a level control key; a storage part for storing RGB gain values and RGB count values; a control part for reading the RGB gain values and the RGB count values from the storage part, for controlling count values of selected colors according to an input state of the color selection key and an input state of the level control key, for calculating difference values by comparing count values of the controlled colors with count values of the other colors not controlled, for controlling the RGB gain values according to the calculated difference values, and for updating the controlled count values and gain values in the storage part; and a video processing part for controlling a magnitude of the RGB video signal based on the RGB gain values controlled in the control part, and for displaying the controlled magnitude of the RGB video signal on a cathode ray tube.
In order to achieve the above object, the method for controlling a video signal gain in a video display device according to the present invention comprises the steps of: controlling the magnitude of an RGB video signal by controlling RGB gain values based on RGB count values controlled through external key inputs; reading the RGB gain values and the RGB count values stored in a storage part; receiving inputs from an RGB color selection key; receiving inputs from a level control key; reading the color count values selected by the RGB color selection key input and controlling the color count values according to the level control key input; calculating difference values through a comparison of the color count values controlled in the preceding step with the other color count values read from the storage part and controlling the RGB gain values according to the calculated difference values; and updating the count values and the gain values controlled in the two preceding steps.
Accordingly, by controlling the RGB gain values according to the difference values calculated through a comparison of color count values controlled by a user with the other color count values not controlled, the brightness is not greatly increased or decreased and constant color coordinates are maintained when the RGB gains are controlled.